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Old 10-09-2012, 09:28 PM   #1 (permalink)
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"Tiny" Side View Mirror

Side view mirrors add to frontal area and create a lot of turblance which is not good for the aerodynamics of a vehicle.

A total mirror delete with the addition of a camera to take it's place would be ideal. However, besides the high cost, you are not allowed by the law to replace your mirrors with cameras (yet). Moving a mirror to the interior of a vehicle along with the view that is provided is inferior compared to a outside mirror.

So, what can one do...???


Answer.


Replace a existing mirror with this...



It is a mirror for a bicycle bought at Walmart for $6.99 .



The mirror transplant patient.




The original mirror.




Old mirror removed and hole drilled for the new mirror.




Picture of the new mirror disassembled.




New mirror installed.








Comparing the original to the new mirror.




New mirror is approximately 3sq.inches.

Old mirror is 10-15x that total. (size of mirror and mounting)

Since the new mirror is adjustable in 3 axis, it was easy to mount to the face of the door and still have a level point of view.

One could mount this mirror to a variety of vehicles with ease.


So...

Whats it like...???

Well, I took it for a spin and was pleased with the result...
The field of view is pretty good. Also, it is quieter than the original. It is however like most other auto mirrors as the vehicles viewed are closer than they appear. Just so you know, the mirror is made of plastic and will probably scratch easily so it would have be treated carefully.


Anyway, I hope this novel approach to a problem all our vehicles suffer from
can help someone else.

Have a Great Day...

Redneck

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Old 10-09-2012, 09:40 PM   #2 (permalink)
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Did you fill in the old opening with plastic? Closeup pic of the new mirror from the side, please.
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Old 10-11-2012, 01:43 AM   #3 (permalink)
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redneck -

Great job! I used to have a tiny bicycle one (bottom mirror) :



It would shake a lot because the arm wasn't designed for car speeds. When I was commuting I switched to a motorcycle mirror for the sake of my passenger's nerves and kept it.

Soooooo, I chose the middle way.

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Old 10-11-2012, 02:41 AM   #4 (permalink)
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I've always thought sports motorcycles mirrors are the most effective options, not compromising too much the visibility while retaining a good aerodynamic.
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Old 10-11-2012, 03:51 PM   #5 (permalink)
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Do we have any A-B-A testing on a mod like this? I'm skeptical, although the surface area is smaller, the form of your replacement mirror is less aero than stock.

For example, look at these shapes:

(Source: Wikipedia on Drag Coefficient.)

I'm thinking half-sphere .42, vs short-cylinder 1.15. If the Cd difference were that large (it may not be), you'd have to cut the mirror area by almost 3X just to break even.

The effectiveness of this mod might be 0.

EDIT: Sorry, I was probably being a bit pessimistic. I have a bicycle mirror like that and I remember it being a bit curved on the back side. Also I reread and found where redneck said:
Quote:
New mirror is approximately 3sq.inches.

Old mirror is 10-15x that total. (size of mirror and mounting)
If so then even a 3X increase in Cd would translate to 3-5X decrease in CdA.

But I think my underlying point is valid; be careful selecting a smaller mirror, and A-B-A testing would be interesting.

Last edited by christofoo; 10-11-2012 at 04:09 PM..
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Old 10-11-2012, 04:06 PM   #6 (permalink)
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Why do you say it's less aero than stock?
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Old 10-11-2012, 04:11 PM   #7 (permalink)
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Quote:
Originally Posted by Sven7 View Post
Why do you say it's less aero than stock?
I just meant higher Cd than stock. The backside of the mirror is more blunt. Also see my edit.
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Old 10-11-2012, 04:17 PM   #8 (permalink)
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Quote:
Originally Posted by christofoo View Post
Do we have any A-B-A testing on a mod like this? I'm skeptical, although the surface area is smaller, the form of your replacement mirror is less aero than stock.

For example, look at these shapes:

(Source: Wikipedia on Drag Coefficient.)

I'm thinking half-sphere .42, vs short-cylinder 1.15. If the Cd difference were that large (it may not be), you'd have to cut the mirror area by almost 3X just to break even.

The effectiveness of this mod might be 0.

EDIT: Sorry, I was probably being a bit pessimistic. I have a bicycle mirror like that and I remember it being a bit curved on the back side. Also I reread and found where redneck said:


If so then even a 3X increase in Cd would translate to 3-5X decrease in CdA.

But I think my underlying point is valid; be careful selecting a smaller mirror, and A-B-A testing would be interesting.
I have this mirror on 3 of my bikes. The backside of the mirror is flat for about 5/8 of its area, then the corners are rounded with the radius approximately equal to 3/4 of the mirror thickness. Imagine the half-sphere with the nose area flattened. So I think the Cd would be somewhere in between the half-sphere and short cylinder, probaby closer to the half-sphere. Also, it would probably be easy to mold some modelling clay on the back to round it into more of a nose cone shape.
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Old 10-11-2012, 04:24 PM   #9 (permalink)
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Quote:
Originally Posted by Patrick View Post
I have this mirror on 3 of my bikes. The backside of the mirror is flat for about 5/8 of its area, then the corners are rounded with the radius approximately equal to 3/4 of the mirror thickness. Imagine the half-sphere with the nose area flattened. So I think the Cd would be somewhere in between the half-sphere and short cylinder, probaby closer to the half-sphere. Also, it would probably be easy to mold some modelling clay on the back to round it into more of a nose cone shape.
My excuse is I was off thinking about some flatter mirrors I saw at the auto parts store when I started writing. Still on the line of thinking that steered me away from those.

I think your analysis is right. Maybe I should just say I was wrong.

EDIT: you could also do the Bondo-on-foam method instead of modeling clay.
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Old 10-11-2012, 04:38 PM   #10 (permalink)
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Quote:
Originally Posted by Patrick View Post
Did you fill in the old opening with plastic? Closeup pic of the new mirror from the side, please.
I used black duct tape to fill the opening at first. I wanted to see if I liked it or not before going further. Today, I made a replacement piece from a 1/8" thick foam sheet and attached it with weather stripping adhesive.



The Dime in the picture is for size reference.



Not the best looking, but good enough for now.

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